Re: module needs another module for build

[bingos]

in reply to module needs another module for build

build_requires will be resolved too late to be of any help. build_requires are resolved by *after* Makefile.PL has already been executed by cpan/cpanp/cpanm etc.

CONFIGURE_REQUIRES on the other hand are a list of prereqs that must be resolved *before* Makefile.PL is executed.

• CONFIGURE_REQUIRES - modules required by Makefile.PL/Build.PL
• BUILD_REQUIRES - modules required only during the build process
• PREREQ_PM - modules required to run your module

WriteMakefile(
   CONFIGURE_REQUIRES => {
          'B' => 0,
   },
   PREREQ_PM => {
          'B' => 0,
   },
)

We require the 'B' module during configuration and at runtime in the above example.

[dk]

Thank you! CONFIGURE_REQUIRES is definitely a step forward, will try. I wonder if CPAN shell can detect that this field has changed after Makefile.PL was run and re-run it, because I have another module that does just that, if none of the libraries it needs are found, it falls back on a third-party module.

[bingos]

The CPAN clients (cpan/cpanp/cpanm) take the following steps:

• Download distribution
• Extract distribution
• Does a META.yml or META.json file exist? Okay, parse and look for configure_requires, resolve all the requirements listed there
• Execute Makefile.PL or Build.PL
• If there is a MYMETA.yml or MYMETA.json, parse and look for build and runtime requirements, resolve these
• No, MYMETA files, okay, if there is a Makefile parse that to resolve requirements
• Oh, its a Module::Build based dist, try running 'Build prereq_data' action, if that fails, poke around in _build/ directory to find the requirements
• Resolve requirements
• Execute 'make' for EUMM or './Build' for M::B
• Execute 'make test' for EUMM or './Build test' for M::B
• Execute 'make install' for EUMM or './Build install' for M::B

[dk]

++ very useful , thanks. This should be in FAQ somewhere.